Apply suggestion from @gastmaier

Co-authored-by: Jorge Marques <2892061+gastmaier@users.noreply.github.com>
Signed-off-by: Sabolik <55389620+Sabolik@users.noreply.github.com>

Author: Sabolik

labgrid/util/agents/visa_instrument.py

@@ -18,17 +18,16 @@ def __init__(self, device_identifier, backend, timeout):
         try:
             _py_pyvisa_module = import_module('pyvisa')
         except ModuleNotFoundError as e:
-            raise ModuleNotFoundError("pyvisa module not found, please install it") from e
-        else:
-            _pyvisa_resource_manager = _py_pyvisa_module.ResourceManager(backend)
-            if _pyvisa_resource_manager is None:
-                raise ValueError("pyVISA backend not found")
-            self._pyvisa_device = _pyvisa_resource_manager.open_resource(device_identifier)
-            if 'SOCKET' in device_identifier:
-                self._pyvisa_device.read_termination = '\n'
-                self._pyvisa_device.write_termination = '\n'
-            if self._pyvisa_device is None:
-                raise ValueError("pyVISA device not found")
+        if not importlib.util.find_spec("pyvisa"):
+            raise ModuleNotFoundError("pyvisa module not found, please install it")
+		
+        _py_pyvisa_module = import_module('pyvisa')
+        _pyvisa_resource_manager = _py_pyvisa_module.ResourceManager(backend)
+        if _pyvisa_resource_manager is None:
+            raise ValueError("pyVISA backend not found")
+        self._pyvisa_device = _pyvisa_resource_manager.open_resource(device_identifier)
+        if self._pyvisa_device is None:
+            raise ValueError("pyVISA device not found
             try:
                 self._pyvisa_device.clear()
             except _py_pyvisa_module.errors.VisaIOError as e: