Update spice::readValue to throw an exception if no values are read (D…

…OI-USGS#5165)

* Modified spice::readValue to add check for numValuesRead

* Updated changelog

* Added an exception when no value is read in Spice::readValue

CHANGELOG.md

@@ -48,6 +48,7 @@ release.
 ### Fixed
 - Updated README.md to remove remaining references to downloading data from discontinued rsync server [#5152](https://github.com/DOI-USGS/ISIS3/issues/5152)
 - Fixed users not being able to modify planetographic projections in qmos
+- Modified spice::readValue to add check for numValuesRead to stop reading garbase values [#4928](https://github.com/USGS-Astrogeology/ISIS3/issues/4928)
 
 ## [7.2.0] - 2022-12-07
 

isis/src/base/objs/Spice/Spice.cpp

@@ -1118,30 +1118,34 @@ namespace Isis {
         gdpool_c(key.toLatin1().data(), (SpiceInt)index, 1,
                  &numValuesRead, &kernelValue, &found);
 
-        if (found)
+        if (found && numValuesRead > 0)
           result = kernelValue;
       }
       else if (type == SpiceStringType) {
         char kernelValue[512];
         gcpool_c(key.toLatin1().data(), (SpiceInt)index, 1, sizeof(kernelValue),
                  &numValuesRead, kernelValue, &found);
 
-        if (found)
+        if (found && numValuesRead > 0)
           result = kernelValue;
       }
       else if (type == SpiceIntType) {
         SpiceInt kernelValue;
         gipool_c(key.toLatin1().data(), (SpiceInt)index, 1, &numValuesRead,
                  &kernelValue, &found);
 
-        if (found)
+        if (found && numValuesRead > 0)
           result = (int)kernelValue;
       }
 
       if (!found) {
         QString msg = "Can not find [" + key + "] in text kernels";
         throw IException(IException::Io, msg, _FILEINFO_);
       }
+      else if (numValuesRead == 0){
+        QString msg = "Found " + key + "] in text kernels, but no values were identified and read.";
+        throw IException(IException::Io, msg, _FILEINFO_);
+      }
 
       storeValue(key, index, type, result);
       NaifStatus::CheckErrors();