Use thiserror for error handling with less boilerplate

src/multi/generic_multiple_barcode_reader.rs

@@ -56,7 +56,7 @@ impl<T: Reader> MultipleBarcodeReader for GenericMultipleBarcodeReader<T> {
         let mut results = Vec::new();
         self.doDecodeMultiple(image, hints, &mut results, 0, 0, 0);
         if results.is_empty() {
-            return Err(Exceptions::notFound);
+            return Err(Exceptions::NOT_FOUND);
         }
         Ok(results)
     }

src/multi/qrcode/detector/multi_detector.rs

@@ -50,7 +50,7 @@ impl<'a> MultiDetector<'_> {
         let infos = finder.findMulti(hints)?;
 
         if infos.is_empty() {
-            return Err(Exceptions::notFound);
+            return Err(Exceptions::NOT_FOUND);
         }
 
         let mut result = Vec::new();

src/multi/qrcode/detector/multi_finder_pattern_finder.rs

@@ -92,7 +92,7 @@ impl<'a> MultiFinderPatternFinder<'_> {
 
         if size < 3 {
             // Couldn't find enough finder patterns
-            return Err(Exceptions::notFoundWith(
+            return Err(Exceptions::not_found_with(
                 "Couldn't find enough finder patterns",
             ));
         }
@@ -212,7 +212,7 @@ impl<'a> MultiFinderPatternFinder<'_> {
         if !results.is_empty() {
             Ok(results)
         } else {
-            Err(Exceptions::notFound)
+            Err(Exceptions::NOT_FOUND)
         }
     }
 

src/multi/qrcode/qr_code_multi_reader.rs

@@ -111,7 +111,7 @@ impl MultipleBarcodeReader for QRCodeMultiReader {
                 // ignore and continue
                 continue;
             } else {
-                return Err(output.err().unwrap_or(Exceptions::notFound));
+                return Err(output.err().unwrap_or(Exceptions::NOT_FOUND));
             }
         }