Tensorflow check and extras README (#135)

README.md

@@ -31,7 +31,7 @@ pip install modelscan
 With it installed, scan a model:
 
 ```bash
-modelscan -p /path/to/model_file.h5
+modelscan -p /path/to/model_file.pkl
 ```
 
 ## Why You Should Scan Models
@@ -105,6 +105,11 @@ or `pyproject.toml` like this:
 modelscan = ">=0.1.1"
 ```
 
+Scanners for Tensorflow or HD5 formatted models require installation with extras:
+```bash
+pip install 'modelscan[ tensorflow, h5py ]'
+```
+
 ### Using ModelScan via CLI
 
 ModelScan supports the following arguments via the CLI:

modelscan/scanners/saved_model/scan.py

@@ -64,7 +64,9 @@ def _check_for_unsafe_tf_keras_operator(
         unsafe_operators: Dict[str, Any],
     ) -> ScanResults:
         issues: List[Issue] = []
-        all_operators = tensorflow.raw_ops.__dict__.keys()
+        all_operators = (
+            tensorflow.raw_ops.__dict__.keys() if tensorflow_installed else []
+        )
         all_safe_operators = [
             operator for operator in list(all_operators) if operator[0] != "_"
         ]