Fix: raise OptionalImportError when user-specified reader package is not installed

Author: Talhax55z

monai/transforms/io/array.py

@@ -210,10 +210,10 @@ def __init__(
                     the_reader = look_up_option(_r.lower(), SUPPORTED_READERS)
                 try:
                     self.register(the_reader(*args, **kwargs))
-                except OptionalImportError:
-                    warnings.warn(
+                except OptionalImportError as e:
+                    raise OptionalImportError(
                         f"required package for reader {_r} is not installed, or the version doesn't match requirement."
-                    )
+                    ) from e
                 except TypeError:  # the reader doesn't have the corresponding args/kwargs
                     warnings.warn(f"{_r} is not supported with the given parameters {args} {kwargs}.")
                     self.register(the_reader())