devtool: use DevtoolError for error handling

Use DevtoolError exception more widely for handling error cases. This
exception is now caught in the main script and raising it can be used to
exit with an error. This hopefully simplifies error handling. The
change also makes exit codes more consistent, always returning '1' when
an error occurs.

(From OE-Core rev: 2e4f1dcade7ccb581c7a390c32163ea3deeac6d5)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/devtool

@@ -35,6 +35,7 @@ context = None
 scripts_path = os.path.dirname(os.path.realpath(__file__))
 lib_path = scripts_path + '/lib'
 sys.path = sys.path + [lib_path]
+from devtool import DevtoolError
 import scriptutils
 logger = scriptutils.logger_create('devtool')
 
@@ -250,7 +251,12 @@ def main():
     if args.subparser_name != 'create-workspace':
         read_workspace()
 
-    ret = args.func(args, config, basepath, workspace)
+    try:
+        ret = args.func(args, config, basepath, workspace)
+    except DevtoolError as err:
+        if str(err):
+            logger.error(str(err))
+        ret = 1
 
     return ret