Troubleshooting Deno Doc HTML Generation Panics A Comprehensive Guide

by ADMIN 70 views
Iklan Headers

Hey guys! Ever run into a frustrating issue while trying to generate documentation with Deno? Specifically, a panic when using the --html flag with deno doc? I recently faced this exact problem and wanted to share my experience and potential solutions with you. Let's dive in!

Understanding the Deno Doc Panic

So, you're cruising along, building your awesome Deno project, and you decide it's time to generate some sweet, sweet HTML documentation using deno doc --html ./_docs.ts. But then, BAM! A scary-looking panic message appears, telling you that "Deno has panicked" and that it's a bug. Ugh, nobody likes seeing that, right?

============================================================
Deno has panicked. This is a bug in Deno. Please report this
at https://github.com/denoland/deno/issues/new.
If you can reliably reproduce this panic, include the
reproduction steps and re-run with the RUST_BACKTRACE=1 env
var set and include the backtrace in your report.

Platform: macos x86_64
Version: 2.4.2
Args: ["deno", "doc", "--html", "./_docs.ts"]

View stack trace at:
https://panic.deno.com/v2.4.2/x86_64-apple-darwin/qogxQi-k3_BqvtmgCyotmgC4v8mgC-hgh9Dmpjh9D4npybyzjyb6vhyb471wbukmvb085ubs_l4bwrlpO-rznOwvxtQ8owFs1u1G6suxQgo12Dsgm2R

thread 'main' panicked at library/core/src/slice/sort/shared/smallsort.rs:865:5:
user-provided comparison function does not correctly implement a total order
stack backtrace:
   0:        0x102cbc14c - _node_api_get_module_file_name
   1:        0x101685193 - __mh_execute_header
   2:        0x102cbac42 - _node_api_get_module_file_name
   3:        0x102cbbfa3 - _node_api_get_module_file_name
   4:        0x102cbb22d - _node_api_get_module_file_name
   5:        0x10152213c - __mh_execute_header
   6:        0x102cba9e1 - _node_api_get_module_file_name
   7:        0x102cf7af5 - _node_api_get_module_file_name
   8:        0x102cf7a89 - _node_api_get_module_file_name
   9:        0x102cf98fc - _node_api_get_module_file_name
  10:        0x104b6201f - _node_api_get_module_file_name
  11:        0x104b62693 - _node_api_get_module_file_name
  12:        0x101aa727c - __mh_execute_header
  13:        0x101aa6739 - __mh_execute_header
  14:        0x101aa62fd - __mh_execute_header
  15:        0x101aa0bbc - __mh_execute_header
  16:        0x101a9ac47 - __mh_execute_header
  17:        0x101a993ca - __mh_execute_header
  18:        0x101abebf6 - __mh_execute_header
  19:        0x101402ab8 - __mh_execute_header
  20:        0x1013fc6bf - __mh_execute_header
  21:        0x1015142f8 - __mh_execute_header
  22:        0x100cf408e - __mh_execute_header
  23:        0x101033d56 - __mh_execute_header
  24:        0x101523ccd - __mh_execute_header
  25:        0x100eb8a80 - __mh_execute_header
  26:        0x1015b6c06 - __mh_execute_header

The error message itself can be a bit cryptic, but the key part here is: "user-provided comparison function does not correctly implement a total order." This usually points to an issue within your code, specifically related to how Deno Doc is processing your types and interfaces.

Diving Deeper into the Error

This error typically arises when Deno Doc encounters a situation where it needs to sort some data related to your code's structure, and the comparison logic it's using isn't behaving as expected. A "total order" basically means that for any two items being compared, the comparison function should be able to consistently determine which one comes "before" the other, or if they are equal. If this order is inconsistent (e.g., A < B, B < C, but C < A), then the sorting algorithm can go haywire, leading to a panic. This is very important when working with complex object hierarchies, generics, or advanced type definitions.

Reproducing the Panic (and Why It's Important)

The error message kindly suggests re-running the command with the RUST_BACKTRACE=1 environment variable set. This is crucial because it provides a more detailed stack trace, giving you (and the Deno team if you report the issue) a better idea of exactly where the panic is occurring within Deno's code. It's like having a detailed map to the crash site, instead of just knowing the general area. To do this, you'd run:

RUST_BACKTRACE=1 deno doc --html ./_docs.ts

The output will be much longer, but it'll contain valuable clues to help pinpoint the problem.

Potential Causes and Solutions

Okay, so we know we have a panic related to sorting during HTML documentation generation. What could be causing this, and how can we fix it? Here are some common culprits and strategies:

1. Complex Object Hierarchies and Type Definitions

In my case, and in many others, the issue stems from complex object hierarchies and type definitions within your code. Deno Doc might struggle to fully understand the relationships between your interfaces, types, and classes, especially if you're using advanced TypeScript features like generics, conditional types, or mapped types. When the documentation generator attempts to process these intricate structures, it may encounter scenarios where the sorting logic breaks down.

Solution:

  • Simplify your type definitions: Look for areas where you might be able to reduce complexity. Could you break down large interfaces into smaller, more manageable ones? Are you using generics excessively? Sometimes, refactoring your types can make them easier for Deno Doc to process.
  • Provide explicit type annotations: In some cases, Deno Doc might struggle to infer the types correctly. Adding explicit type annotations can provide clarity and help the documentation generator understand your code better. For example, if you have a function that returns a complex object, explicitly define the return type.
  • Consider using JSDoc comments: JSDoc comments are a standard way to document JavaScript and TypeScript code. They can provide additional information to Deno Doc, helping it understand your code's structure and purpose. Use JSDoc to document your interfaces, types, and functions, especially if they are complex.

2. Circular Dependencies

Another potential cause of this panic is circular dependencies between your modules. If module A depends on module B, and module B depends on module A, this can create a circular dependency. Deno Doc might get stuck in a loop while trying to resolve these dependencies, leading to the sorting issue and the panic.

Solution:

  • Identify and break circular dependencies: Use a tool like deno info or a dependency graph visualizer to identify circular dependencies in your project. Then, refactor your code to eliminate these cycles. This might involve moving shared code into a separate module or using dependency injection techniques.

3. Bugs in Deno Doc (or Deno Itself)

It's also possible that the panic is caused by a bug in Deno Doc or Deno itself. While Deno is generally very stable, bugs can happen, especially in newer versions or with specific edge cases. If you've tried the solutions above and are still encountering the panic, it's worth considering this possibility.

Solution:

  • Check for known issues: Search the Deno issue tracker on GitHub to see if anyone else has reported a similar problem. If so, there might be a known workaround or a fix in progress.
  • Try a different Deno version: If you're using the latest version of Deno, try downgrading to a previous version to see if the issue goes away. This can help determine if the panic is related to a recent change.
  • Report the issue to the Deno team: If you suspect a bug in Deno, report it on the Deno issue tracker. Be sure to include a clear description of the problem, the steps to reproduce it, and the output of RUST_BACKTRACE=1 deno doc --html .... The more information you provide, the easier it will be for the Deno team to investigate and fix the issue.

4. Issues with the _docs.ts File

In the original report, the user mentioned using a _docs.ts file that contained a list of all the TypeScript files in their project. This was an attempt to work around Deno Doc's inability to understand the object hierarchy. While this might seem like a clever workaround, it can sometimes lead to problems.

Solution:

  • Avoid manual file lists: Deno Doc is designed to automatically discover and process your project's files. Unless you have a very specific reason to do so, it's generally best to let Deno Doc handle file discovery on its own. Remove the _docs.ts file and try running deno doc --html on your main entry point or module.
  • Ensure correct file paths: If you do need to specify a file list, make sure the paths are correct and that all the files are valid TypeScript files.

Practical Steps to Troubleshoot the Panic

Okay, let's recap and outline a practical approach to troubleshooting this Deno Doc panic:

  1. Reproduce the panic with RUST_BACKTRACE=1: This is your first step. Get that detailed stack trace! It's like the breadcrumbs leading you to the source of the problem.
  2. Analyze the stack trace: Look for clues in the stack trace. Are there any file paths or function names that stand out? This might give you an idea of which part of your code is causing the issue.
  3. Simplify type definitions: If the stack trace points to type-related code, try simplifying your types and interfaces. Add explicit type annotations and consider using JSDoc comments.
  4. Check for circular dependencies: Use deno info or a dependency graph tool to identify and break any circular dependencies in your project.
  5. Try a different Deno version: If you suspect a Deno bug, try downgrading to a previous version.
  6. Report the issue (if necessary): If you've exhausted all other options and still can't resolve the panic, report it to the Deno team on GitHub. Include the stack trace, your Deno version, and a clear description of the problem.

Conclusion

The Deno Doc panic when generating HTML can be a frustrating experience, but by understanding the potential causes and following a systematic troubleshooting approach, you can often resolve the issue. Remember to analyze the stack trace, simplify your types, check for circular dependencies, and consider the possibility of a Deno bug. And don't hesitate to ask for help from the Deno community if you get stuck. Happy documenting, guys!