What this snippet does
Custom error classes let you distinguish error types with instanceof and attach extra context like field names or codes.
Expected output
ValidationError on field 'age': Out of range
Why practise typing this
Typing error handling code builds muscle memory for the symbols and indentation JavaScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
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