Fixed handling errors regarding target detection and flashing

Author: screamerbg

mbed/mbed.py

@@ -2231,19 +2231,19 @@ def compile_(toolchain=None, target=None, profile=False, compile_library=False,
                   + (['-v'] if verbose else [])
                   + args,
                   env=env)
-            
+ 
             if flash:
                 fw_name = artifact_name if artifact_name else program.name
                 fw_fbase = os.path.join(build_path, fw_name)
                 fw_file = fw_fbase + ('.hex' if os.path.exists(fw_fbase+'.hex') else '.bin')
-                if not fw_file:
-                    error("Firmware file not found \"%s\"" % fw_file, 1)
+                if not os.path.exists(fw_file):
+                    error("Build program file (firmware) not found \"%s\"" % fw_file, 1)
                 detected = program.detect_target()
 
                 try:
                     from mbed_host_tests.host_tests_toolbox import flash_dev, reset_dev
                 except (IOError, ImportError, OSError):
-                    error("The '-f' option requires that the 'mbed-greentea' python module is installed.\nYou can install mbed-ls by running 'pip install mbed-greentea'.", 1)
+                    error("The '-f/--flash' option requires that the 'mbed-greentea' python module is installed.\nYou can install mbed-ls by running 'pip install mbed-greentea'.", 1)
 
                 if not flash_dev(detected['msd'], fw_file, program_cycle_s=2):
                     error("Unable to flash the target board connected to your system.", 1)