[BL] ConfigTree: Fix warning "catch by value".

BaseLib/ConfigTree-impl.h

@@ -120,14 +120,20 @@ peekConfigParameter(std::string const& param) const
 {
     checkKeyname(param);
 
-    if (auto p =_tree->get_child_optional(param)) {
-        try {
+    if (auto p = _tree->get_child_optional(param))
+    {
+        try
+        {
             return p->get_value<T>();
-        } catch (boost::property_tree::ptree_bad_data) {
-            error("Value for key <" + param + "> `" + shortString(p->data())
-                  + "' not convertible to the desired type.");
         }
-    } else {
+        catch (boost::property_tree::ptree_bad_data const&)
+        {
+            error("Value for key <" + param + "> `" + shortString(p->data()) +
+                  "' not convertible to the desired type.");
+        }
+    }
+    else
+    {
         error("Key <" + param + "> has not been found");
     }
 }

BaseLib/ConfigTreeUtil.cpp

@@ -54,13 +54,16 @@ makeConfigTree(const std::string& filepath, const bool be_ruthless,
 
     // note: Trimming whitespace and ignoring comments is crucial in order
     //       for our configuration tree implementation to work!
-    try {
+    try
+    {
         read_xml(filepath, ptree,
                  boost::property_tree::xml_parser::no_comments |
-                 boost::property_tree::xml_parser::trim_whitespace);
-    } catch (boost::property_tree::xml_parser_error e) {
+                     boost::property_tree::xml_parser::trim_whitespace);
+    }
+    catch (boost::property_tree::xml_parser_error const& e)
+    {
         OGS_FATAL("Error while parsing XML file `%s' at line %lu: %s.",
-            e.filename().c_str(), e.line(), e.message().c_str());
+                  e.filename().c_str(), e.line(), e.message().c_str());
     }
 
     DBUG("Project configuration from file \'%s\' read.", filepath.c_str());