fix(secrets): fix find line (#6864)

checkov/secrets/plugins/custom_regex_detector.py

@@ -170,12 +170,13 @@ def _find_potential_secret(
                     continue
                 multiline_matches = multiline_regex.findall(file_content)
                 for mm in multiline_matches:
+                    line_num = find_line_number(file_content, mm, line_number)
                     quoted_mm = f"'{mm}'"
                     ps = PotentialSecret(
                         type=regex_data["Name"],
                         filename=filename,
                         secret=quoted_mm,
-                        line_number=find_line_number(file_content, mm, line_number),
+                        line_number=line_num,
                         is_verified=is_verified,
                         is_added=is_added,
                         is_removed=is_removed,
@@ -219,9 +220,12 @@ def analyze_string(self, string: str, **kwargs: Optional[Dict[str, Any]]) -> Gen
 
 
 def find_line_number(file_string: str, substring: str, default_line_number: int) -> int:
-    lines = file_string.splitlines()
-
-    for line_number, line in enumerate(lines, start=1):
-        if substring in line:
-            return line_number
-    return default_line_number
+    try:
+        lines = file_string.splitlines()
+
+        for line_number, line in enumerate(lines, start=1):
+            if substring in line:
+                return line_number
+        return default_line_number
+    except Exception:
+        return default_line_number