fix nix

Signed-off-by: Tushar Goel <tushar.goel.dav@gmail.com>

Author: TG1999

vulnerabilities/importer.py

@@ -188,7 +188,10 @@ def from_dict(cls, affected_pkg: dict):
         """
         package = PackageURL(**affected_pkg["package"])
         affected_version_range = None
-        if affected_pkg["affected_version_range"]:
+        if (
+            affected_pkg["affected_version_range"]
+            and affected_pkg["affected_version_range"] != "None"
+        ):
             affected_version_range = VersionRange.from_string(
                 affected_pkg["affected_version_range"]
             )

vulnerabilities/improvers/default.py

@@ -64,14 +64,14 @@ def get_exact_purls(affected_package: AffectedPackage) -> (List[PackageURL], Pac
     # We need ``if c`` below because univers returns None as version
     # in case of vers:nginx/*
     # TODO: Revisit after https://github.com/nexB/univers/issues/33
-    range_versions = [c.version for c in vr.constraints if c]
-    resolved_versions = [v for v in range_versions if v and v in vr]
-
     affected_purls = []
-    for version in resolved_versions:
-        affected_purl = affected_package.package._replace(version=str(version))
-        affected_purls.append(affected_purl)
+    if vr:
+        range_versions = [c.version for c in vr.constraints if c]
+        resolved_versions = [v for v in range_versions if v and v in vr]
+        for version in resolved_versions:
+            affected_purl = affected_package.package._replace(version=str(version))
+            affected_purls.append(affected_purl)
 
-    fixed_purl = affected_package.get_fixed_purl()
+    fixed_purl = affected_package.get_fixed_purl() if affected_package.fixed_version else None
 
     return affected_purls, fixed_purl