bug(crash): thread panic while loading file diff

Author: sgtrustyCreated Aug 20, 2026Updated Aug 20, 2026

Describe the bug

Error while using lazygit. Visualized below:

Full text stack:

rust

thread 'main' (429902) panicked at src/display/hunks.rs:518:17:
internal error: entered unreachable code: Should be impossible: every LHS Unchanged MatchedPos should have a corresponding RHS Unchanged MatchedPos
  None
  Some(MatchedPos {
    kind: UnchangedToken {
      highlight: Delimiter,
      self_pos: [SingleLineSpan { line: LineNumber: 158 (zero-indexed: 157), start_col: 0, end_col: 1 }],
      opposite_pos: [SingleLineSpan { line: LineNumber: 170 (zero-indexed: 169), start_col: 0, end_col: 1 }]
    },
    pos: SingleLineSpan { line: LineNumber: 158 (zero-indexed: 157), start_col: 0, end_col: 1 }
  })

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal: external diff died, stopping at src/routes/post/upload.tsx

To Reproduce

Before file:

typescript

import React, { Component } from 'react'

interface TagsInputProps {
    tags: string
    onChange: (e: React.ChangeEvent<HTMLInputElement>) => void
}

export class TagsInput extends Component<TagsInputProps> {
    render() {
        return (
            <label className="flex flex-col gap-1.5">
                <span className="text-sm font-medium text-[var(--sea-ink-soft)]">
                    Tags{' '}
                </span>
                <input
                    type="text"
                    value={this.props.tags}
                    onChange={this.props.onChange}
                    placeholder="Tags: nature, sunset, ocean"
                    className="rounded-xl border border-[var(--line)] bg-white/60 px-3 py-2 text-sm text-[var(--sea-ink)] outline-none focus:border-[var(--lagoon-deep)]"
                />
            </label>
        )
    }
}

After file:

typescript

import React, { Component } from 'react'

interface TagsInputProps {
    tags: string
    onChange: (e: React.ChangeEvent<HTMLInputElement>) => void
}

export class TagsInput extends Component<TagsInputProps> {
    render() {
        return (
                    <label className="flex flex-col gap-1.5">
                        <span className="text-sm font-medium text-[var(--sea-ink-soft)]">
                            Tags
                        </span>
                        <input
                            type="text"
                            value={tags}
                            onChange={(e) => setTags(e.target.value)}
                            placeholder="nature, sunset, ocean"
                            className="rounded-xl border border-[var(--line)] bg-white/60 px-3 py-2 text-sm text-[var(--sea-ink)] outline-none focus:border-[var(--lagoon-deep)]"
                        />
                    </label>
        )
    }
}

Expected behavior

Lines should be clearly displayed, maybe parser is broken.

Screenshots

Version info:

Had an older version, updated to latest and same issue:

Originally:

Difftastic 0.69.0

Revision: 90a0f1b6a 2026-04-29 Toolchain: 1.95.0 System: linux x86_64

Updated to 0.70.0-2 and the problem persists!

Terminal info:

ghostty + bash

Additional context

Seems like some issue with whitespace parsing / or the tsx convention {" "} in place of  . Funnily enough, if we change that multiline:

typescript

                        <span className="text-sm font-medium text-[var(--sea-ink-soft)]">
                            Tags
                        </span>

to this:

typescript

                        <span className="text-sm font-medium text-[var(--sea-ink-soft)]">Tags</span>

The diff works as expected.

Source: Wilfred/difftastic

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