twister: remove not needed try..except

Removed redundant try..except around the code
and fixed a test for that code which was false positive.

Signed-off-by: Łukasz Fundakowski <lukasz.fundakowski@nordicsemi.no>
diff --git a/scripts/pylib/twister/twisterlib/environment.py b/scripts/pylib/twister/twisterlib/environment.py
index 47942ba..e1936f5 100644
--- a/scripts/pylib/twister/twisterlib/environment.py
+++ b/scripts/pylib/twister/twisterlib/environment.py
@@ -23,7 +23,6 @@
 import zephyr_module
 from twisterlib.constants import SUPPORTED_SIMS
 from twisterlib.coverage import supported_coverage_formats
-from twisterlib.error import TwisterRuntimeError
 from twisterlib.log_helper import log_command
 
 logger = logging.getLogger('twister')
@@ -1192,11 +1191,8 @@
         toolchain_script = Path(ZEPHYR_BASE) / Path('cmake/verify-toolchain.cmake')
         result = self.run_cmake_script([toolchain_script, "FORMAT=json"])
 
-        try:
-            if result['returncode']:
-                raise TwisterRuntimeError(f"E: {result['returnmsg']}")
-        except Exception as e:
-            print(str(e))
+        if result['returncode'] != 0:
+            print(f"E: {result['returnmsg']}")
             sys.exit(2)
         self.toolchain = json.loads(result['stdout'])['ZEPHYR_TOOLCHAIN_VARIANT']
         logger.info(f"Using '{self.toolchain}' toolchain.")
diff --git a/scripts/tests/twister/test_environment.py b/scripts/tests/twister/test_environment.py
index 33f0c3a..ad2b565 100644
--- a/scripts/tests/twister/test_environment.py
+++ b/scripts/tests/twister/test_environment.py
@@ -7,16 +7,15 @@
 Tests for environment.py classes' methods
 """
 
-from unittest import mock
 import os
-import pytest
 import shutil
-
 from contextlib import nullcontext
+from unittest import mock
+
+import pytest
 
 import twisterlib.environment
 
-
 TESTDATA_1 = [
     (
         None,
@@ -538,7 +537,7 @@
         'Using \'dummy toolchain\' toolchain.'
     ),
     (
-        {'returncode': 1},
+        {'returncode': 1, "returnmsg": "something went wrong"},
         2,
         None
     ),
@@ -572,7 +571,7 @@
             twisterlib.environment.TwisterEnv,
             'run_cmake_script',
             mock.Mock(return_value=script_result)), \
-         pytest.raises(SystemExit) \
+         pytest.raises(SystemExit, match='2') \
             if exit_value is not None else nullcontext() as exit_info:
         twister_env.get_toolchain()