Add variable name to ReferenceError

[Jarred-Sumner]

After:

1 | const fetch = await fetch("https://example.com");
                        ^
ReferenceError: Cannot access 'fetch' before initialization.
      at /Users/jarred/Code/bun/hey.js:1:21

Before:

1 | const fetch = await fetch("https://example.com");
                        ^
ReferenceError: Cannot access uninitialized variable.
      at /Users/jarred/Code/bun/hey.js:1:21