added protection against empty get_found_bp result.

Author: Mohamed Ikbel Boulabiar

include/crow/routing.h

@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <type_traits>
 #include <optional>
+#include <limits>
 
 #include "crow/common.h"
 #include "crow/http_response.h"
@@ -721,7 +722,6 @@ namespace crow // NOTE: Already documented in "crow/app.h"
 
     constexpr size_t RULE_SPECIAL_REDIRECT_SLASH = 1;
 
-
     /// A search tree.
     class Trie
     {
@@ -1317,7 +1317,9 @@ namespace crow // NOTE: Already documented in "crow/app.h"
 
             ruleObject->foreach_method([&](int method) {
                 per_methods_[method].rules.emplace_back(ruleObject);
-                per_methods_[method].trie.add(rule, per_methods_[method].rules.size() - 1, BP_index != INVALID_BP_ID ? blueprints[BP_index]->prefix().length() : 0, BP_index);
+                per_methods_[method].trie.add(rule, per_methods_[method].rules.size() - 1,
+                    BP_index != INVALID_BP_ID ? blueprints[BP_index]->prefix().length() : 0,
+                    BP_index);
 
                 // directory case:
                 //   request to '/about' url matches '/about/' rule
@@ -1528,11 +1530,12 @@ namespace crow // NOTE: Already documented in "crow/app.h"
         CatchallRule& get_catch_all(const routing_handle_result& found) {
             std::vector<Blueprint*> bps_found;
             get_found_bp(found.blueprint_indices, blueprints_, bps_found);
-            for (int i = bps_found.size() - 1; i > 0; i--)
-            {
-                std::vector<size_t> bpi = found.blueprint_indices;
-                if (bps_found[i]->catchall_rule().has_handler()) {
-                    return bps_found[i]->catchall_rule();
+            if (!bps_found.empty()) {
+                for (size_t i = bps_found.size() - 1; i > 0; i--)
+                {
+                    if (bps_found[i]->catchall_rule().has_handler()) {
+                        return bps_found[i]->catchall_rule();
+                    }
                 }
             }
             return catchall_rule_;
@@ -1544,20 +1547,17 @@ namespace crow // NOTE: Already documented in "crow/app.h"
 
             std::vector<Blueprint*> bps_found;
             get_found_bp(found.blueprint_indices, blueprints_, bps_found);
-            for (int i = bps_found.size() - 1; i > 0; i--)
-            {
-                std::vector<size_t> bpi = found.blueprint_indices;
-                if (bps_found[i]->catchall_rule().has_handler())
-                {
+            if (!bps_found.empty()) {
+                for (size_t i = bps_found.size() - 1; i > 0; i--) {
+                    if (bps_found[i]->catchall_rule().has_handler()) {
 #ifdef CROW_ENABLE_DEBUG
-                    return std::string("Redirected to Blueprint \"" + bps_found[i]->prefix() + "\" Catchall rule");
+                        return std::string("Redirected to Blueprint \"" + bps_found[i]->prefix() + "\" Catchall rule");
 #else
-                    return EMPTY;
+                        return EMPTY;
 #endif
+                    }
                 }
-            }
-            if (catchall_rule_.has_handler())
-            {
+            } else  if (catchall_rule_.has_handler()) {
 #ifdef CROW_ENABLE_DEBUG
                 return std::string("Redirected to global Catchall rule");
 #else