dev.7, fix crash

CHANGELOG_LATEST.md

@@ -12,6 +12,8 @@ For more details go to [emsesp.org](https://emsesp.org/).
 
 - signed value for solarInfuence [#3077](https://github.com/emsesp/EMS-ESP32/issues/3077)
 - set bin file upload limit to 1M again [3086](https://github.com/emsesp/EMS-ESP32/issues/3086)
+- check arithmetric operations on strings [#3127](https://github.com/emsesp/EMS-ESP32/discussions/3127)
+- Prevent system crash during WiFi network discovery on ESP32-S3 hardware [#3128](https://github.com/emsesp/EMS-ESP32/pull/3128)
 
 ## Changed
 

src/core/shuntingYard.cpp

@@ -333,7 +333,10 @@ std::deque<Token> shuntingYard(const std::deque<Token> & tokens) {
 
 // check if string is a number
 bool isnum(const std::string & s) {
-    if (!s.empty() && (s.find_first_not_of("0123456789.") == std::string::npos || (s[0] == '-' && s.find_first_not_of("0123456789.", 1) == std::string::npos))) {
+    if (s.empty() || s.find_first_of("0123456789") == std::string::npos) {
+        return false;
+    }
+    if (s.find_first_not_of("0123456789.") == std::string::npos || (s[0] == '-' && s.find_first_not_of("0123456789.", 1) == std::string::npos)) {
         return true;
     }
     return false;
@@ -636,6 +639,10 @@ std::string calculate(const std::string & expr) {
                 stack.push_back(lhs + rhs);
                 break;
             }
+            if (!isnum(rhs) || !isnum(lhs)) {
+                stack.push_back(lhs + token.str + rhs);
+                break;
+            }
             auto lhd = std::stod(lhs);
             auto rhd = std::stod(rhs);
             switch (token.str[0]) {

src/emsesp_version.h

@@ -1 +1 @@
-#define EMSESP_APP_VERSION "3.8.3-dev.6"
+#define EMSESP_APP_VERSION "3.8.3-dev.7"