Navigate to source link ends up in random unrelated files

**Version Used**: Insiders [11925.187] / Compiler version: '5.8.0-1.26319.2 (375c93f06396eff88a355bc473d1586bf71befb5)'. Language version: 14.0.

**Steps to Reproduce**:

1. Checkout https://github.com/Suchiman/NavigationBug
2. In Program.cs:12 place the cursor on `GetOrDefault` and hit F12 whilst "Enable navigation to Source Link and Embedded sources" is enabled
3. Unrelated class `JsonIgnoreCompositeRootConverterFactory` is opened

**Expected Behavior**:
Navigates to the InputExtensions

**Actual Behavior**:
Navigates to line 1 of unrelated `JsonIgnoreCompositeRootConverterFactory` class

Reproduce the issue using the Suchiman/NavigationBug project, with the cursor on GetOrDefault in Program.cs:12 and Source Link and Embedded sources enabled. Compare the navigation result with the expected InputExtensions source and the actual JsonIgnoreCompositeRootConverterFactory file. Done means F12 opens InputExtensions rather than the unrelated class.

Written by the indexing model from the issue text.