More clean up of get_digitizer_peaks()

src/toolbox_scs/detectors/digitizers.py

@@ -939,27 +939,27 @@ def get_digitizer_peaks(run, mnemonics=None, merge_with=None,
     # find digitizer type and get the list of mnemonics to process
     def to_processed_name(name):
         return name.replace('raw', 'peaks').replace('apd', 'peaks')
-    if isinstance(mnemonics, str):
-        mnemonics = [mnemonics]
-        digitizer = digitizer_type(mnemonics[0], run_mnemonics)
-    else:
-        # find mnemonics to process in merge_with
-        for v in merge_with:
-            if 'FastADC2_' in v:
-                digitizer = 'FastADC2'
-                break
-            if 'FastADC' in v:
-                digitizer = 'FastADC'
-                break
-            if 'MCP' in v:
-                digitizer = 'ADQ412'
-                break
+    if mnemonics is None:
+        if digitizer is None:
+            for v in merge_with:
+                if 'FastADC2_' in v:
+                    digitizer = 'FastADC2'
+                    break
+                if 'FastADC' in v:
+                    digitizer = 'FastADC'
+                    break
+                if 'MCP' in v:
+                    digitizer = 'ADQ412'
+                    break
         if digitizer is None:
             log.warning(f'No array with digitizer data '
                      'to extract. Skipping.')
             return merge_with
         mnemonics = mnemonics_to_process(mnemonics, merge_with,
                                          digitizer, to_processed_name)
+    else:
+        mnemonics = [mnemonics] if isinstance(mnemonics, str) else mnemonics
+        digitizer = digitizer_type(mnemonics[0], run_mnemonics)
 
     if len(mnemonics) == 0:
         log.info(f'No array with unaligned {digitizer} peaks to extract. '