fluoscan: improve error messages

tomoscan/esrf/scan/fluoscan.py

@@ -116,6 +116,8 @@ class FluoTomoScanBase:
             raise RuntimeError("Detectors not initialized")
 
     def get_metadata_from_h5_file(self):
+        if len(self.detected_folders) == 0:
+            raise ValueError("No detector found, unable to load metadata")
         h5_path = os.path.join(self.scan, self.detected_folders[0])
         h5_files = glob.glob1(h5_path, "*.h5")
         if len(h5_files) > 1:
@@ -145,6 +147,8 @@ class FluoTomoScanBase:
                     )
 
     def detect_detectors(self):
+        if len(self.detected_folders) == 0:
+            raise ValueError("No detector found, unable to detect detectors")
         proj_1_dir = os.path.join(self.scan, "fluofit", self.detected_folders[0])
         detected_detectors = []
         file_names = glob.glob1(proj_1_dir, "IMG_*area_density_ngmm2.tif")
@@ -155,6 +159,8 @@ class FluoTomoScanBase:
         return detected_detectors
 
     def detect_elements(self):
+        if len(self.detected_folders) == 0:
+            raise ValueError("No detector found, unable to detect elements")
         proj_1_dir = os.path.join(self.scan, "fluofit", self.detected_folders[0])
         detector = self.detectors[0]
         file_names = glob.glob1(proj_1_dir, f"IMG_{detector}*area_density_ngmm2.tif")