feat: fix potential null pointer issue in loadPolicyLine() (#439)

Author: sukidayou

src/main/java/org/casbin/jcasbin/persist/Helper.java

@@ -19,6 +19,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 
 import static org.casbin.jcasbin.util.Util.splitCommaDelimited;
 
@@ -40,7 +41,14 @@ public static void loadPolicyLine(String line, Model model) {
 
         String key = tokens[0];
         String sec = key.substring(0, 1);
-        Assertion ast = model.model.get(sec).get(key);
+        Map<String, Assertion> astMap = model.model.get(sec);
+        if(astMap == null) {
+            return;
+        }
+        Assertion ast = astMap.get(key);
+        if(ast == null) {
+            return;
+        }
         List<String> policy = Arrays.asList(Arrays.copyOfRange(tokens, 1, tokens.length));
         ast.policy.add(policy);
         ast.policyIndex.put(policy.toString(), ast.policy.size() - 1);

src/main/java/org/casbin/jcasbin/persist/file_adapter/FileAdapter.java

@@ -154,7 +154,7 @@ public void removePolicy(String sec, String ptype, List<String> rule) {
         }
         try {
             List<String> lines = IOUtils.readLines(new FileInputStream(filePath), Charset.forName("UTF-8"));
-            lines.remove(ruleText);
+            lines.removeIf(line -> line.replaceAll("\\s", "").equals(ruleText.replaceAll("\\s", "")));
             savePolicyFile(String.join("\n", lines));
         } catch (IOException e) {
             e.printStackTrace();