fix @embedFile("") not giving a proper error

Currently, in a debug build of the compiler, `@embedFile("")` is a crash;
in a release build the compiler, `@embedFile("")` is "error: unable to open '': OutOfMemory".
72ac37952er00ster91 committed on 7/21/2023, 9:39:42 PMparent279ebab
2 files changedLine totals unavailable