Make sure we don't crash on empty lists and we don't divide by zero

common.cpp

@@ -51,6 +51,8 @@ static std::string string_mangle(const std::string& str) {
 }
 
 void show_histogram(const pCaches& cc, std::string Cache::*ptr, const std::string& caption, bool html, bool sort_by_val) {
+	if (cc.empty()) return;
+
 	std::map<std::string, int> histogram;
 
 	for (auto el : cc)
@@ -60,6 +62,8 @@ void show_histogram(const pCaches& cc, std::string Cache::*ptr, const std::strin
 }
 
 void show_histogram(const Caches& cc, std::string Cache::*ptr, const std::string& caption, bool html, bool sort_by_val) {
+	if (cc.empty()) return;
+
 	std::map<std::string, int> histogram;
 
 	for (auto el : cc)
@@ -69,6 +73,8 @@ void show_histogram(const Caches& cc, std::string Cache::*ptr, const std::string
 }
 
 void show_histogram(const std::map<std::string, int>& data, const std::string& caption, bool html, bool sort_by_val) {
+	if (data.empty()) return;
+
 	int HIST_MAX = 20;
 
 	std::vector<std::pair<std::string, int>> pairs;
@@ -118,6 +124,8 @@ void show_histogram(const std::map<std::string, int>& data, const std::string& c
 }
 
 void show_nested_histogram(const pCaches& fcc, std::string Cache::*ptr, std::string Cache::*ptr2, const std::string& caption, bool html, bool sort_by_val) {
+	if (fcc.empty()) return;
+
 	std::map<std::string, int> histogram;
 	std::vector<std::pair<std::string, int>> pairs;
 

geostat.cpp

@@ -828,7 +828,7 @@ int main(int argc, char** argv) {
 		for (auto el : fcc)
 			region_found_count[el->region]++;
 		for (auto& i : region_count)
-			i.second = region_found_count[i.first] * 100 / i.second;
+			if (i.second != 0) i.second = region_found_count[i.first] * 100 / i.second;
 		show_histogram(region_count, "Percentage", 1);
 	}