Dropped the use of exceptions.

I tried the codebase against the new esp-idf 4 alpha code, and
the build didn't have exception handling enabled by default.
I saw no problems with modifying the code to not raise exceptions,
so I did so to be future-proof.

The exception cases were cases that should not happen anyway,
because the input that could trigger the exception has already
been validated on beforehand by the Python-based code generation.

light/color_instant_handler.h

@@ -41,8 +41,10 @@ class ColorInstantHandler : public GPIOOutputs {
       white_light_->copy_to(this);
     else if (rgb_light_->set_light_color_values(v))
       rgb_light_->copy_to(this);
-    else
-      throw std::logic_error("None of the GPIOOutputs classes handles the requested light state");
+    else {
+      ESP_LOGE(TAG, "Light color error: (None of the GPIOOutputs classes handles the requested light state; defaulting to 'off'");
+      off_light_->copy_to(this);
+    }
 
     return true;
   }

light/color_white_light.h

@@ -119,7 +119,10 @@ class ColorWhiteLight : public GPIOOutputs {
     for (RGBWLevelsByTemperature& item : table)
       if (temperature >= item.from_temperature)
         return item;
-    throw std::invalid_argument("received too low temperature");
+    // Temperature too low. Shouldn't happen, because of validation
+    // at higher levels. But when it happens, simply return the data
+    // for lowest available temperature.
+    return table[0];
   }
 };