Given the erroneous sketch
#include <thisLibraryDoesNotExist.h>
void setup() {}
void loop() {}
Arduino 1.5.2 and later fail to report the error
Arduino 1.0.5 and earlier report the error
sketch_feb03a.ino:1:37: warning: thisLibraryDoesNotExist.h: No such file or directory
Peace
--Devon