This is the smallest TypeScript program which validates a coherent error. Use this for whatever purpose you need.
file.ts:1:7 - error TS2322: Type 'number' is not assignable to type 'string'.
1 const a: string = 0;
~
Found 1 error in file.ts:1
> tsc --extendedDiagnostics
Files: 2
Lines of Library: 0
Lines of Definitions: 8
Lines of TypeScript: 2
Lines of JavaScript: 0
Lines of JSON: 0
Lines of Other: 0
Identifiers: 10
Symbols: 17
Types: 75
Instantiations: 0
Memory used: 23525K
Assignability cache size: 0
Identity cache size: 0
Subtype cache size: 0
Strict subtype cache size: 0
I/O Read time: 0.00s
Parse time: 0.00s
Program time: 0.00s
Bind time: 0.00s
Check time: 0.01s
printTime time: 0.00s
Emit time: 0.00s
Total time: 0.01s