Fix signature help crash with colon-prefixed parameters

[richardm90]

Fix signature help crash with colon-prefixed parameters

Issue

Fixes #459

When typing a colon (:) as the first character in a BIF parameter (e.g., changing %scan(code); to %scan(:code);), the signature help provider would crash with:

Root Cause

The Statement.getParameters() method in language/statement.ts was attempting to access newBlock[0].range without checking if newBlock was empty. When a separator (:) appeared as the first token in a parameter position, newBlock would be empty, causing the error.

Changes

• language/statement.ts:35: Added guard condition if (newBlock.length > 0) before accessing newBlock[0].range
• tests/suite/basics.test.ts:2071-2135: Added comprehensive unit test statementGetParametersEmptyBlock that directly tests the fix

Test Coverage

The new test validates:

1. Single separator as first token: [':'] (the bug scenario)
2. Multiple consecutive separators: [':', ':']
3. Normal case with content before separator: ['code', ':', 'str']

Checklist

• have tested my change
• updated relevant documentation
• Remove any/all console.logs I added
• eslint is not complaining
• have added myself to the contributors' list in the README
• for feature PRs: PR only includes one feature enhancement.

[SanjulaGanepola]

@richardm90 Thanks for looking into this and great test cases. After manually testing it, I noticed there was still an issue in the signature help:

With the current changes, the first parameter is highlighted even when the cursor is on the second parameter:

With the suggested changes below, this is fixed:

[richardm90]

@SanjulaGanepola , good catch, I'll take a look.

[richardm90]

@SanjulaGanepola, all of those changes were good and I've applied and tested them.