fix: Fix bug in IF block generators.

[michaela-mm]

The basics

• I validated my changes

The details

Resolves

Fixes #8778 .

Proposed Changes

Check if 'ELSE' input exists before trying to generate code, since generator.statementToCode now throws instead of returning empty string.

Reason for Changes

When STATEMENT_SUFFIX is defined and no 'ELSE' is present, the IF block generator adds an empty 'ELSE' branch anyway - this way e.g. highlighting works correctly. So there is a code path that wants to generate code for the else branch even when the input doesn't exist.

Test Coverage

I tested manually in playground by adding suffixes for all languages and generating code for various IF block configurations.

Documentation

Additional Information

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