Replace all debug_backtrace boilerplate with get_backtrace_loc

pinc/CharSuites.inc

@@ -88,11 +88,8 @@ class CharSuite
         }
 
         // If we don't recognize the property, raise a notice and return null
-        $trace = debug_backtrace();
         trigger_error(
-            'Undefined property via __get(): ' . $name .
-            ' in ' . $trace[0]['file'] .
-            ' on line ' . $trace[0]['line'],
+            "Undefined property via __get(): $name " . get_backtrace_loc(),
             E_USER_NOTICE
         );
         return null;
@@ -105,11 +102,8 @@ class CharSuite
             $this->_pickerset->name = $this->name;
         } else {
             // If we don't recognize the property, raise a notice
-            $trace = debug_backtrace();
             trigger_error(
-                'Undefined property via __get(): ' . $name .
-                ' in ' . $trace[0]['file'] .
-                ' on line ' . $trace[0]['line'],
+                "Undefined property via __set(): $name " . get_backtrace_loc(),
                 E_USER_NOTICE
             );
         }

pinc/DPDatabase.inc

@@ -123,10 +123,9 @@ final class DPDatabase
     {
         // Log the SQL error to the PHP error log and return a generic error
         // for display to the user
-        $backtrace = debug_backtrace();
-        $caller = $backtrace[$backtrace_level]['file'] . ":" . $backtrace[$backtrace_level]['line'];
+        $from_caller = get_backtrace_loc($backtrace_level + 1);
         $error = str_replace("\n", "\\n", mysqli_error(DPDatabase::get_connection()));
-        error_log("DPDatabase.inc - log_error from $caller: $error");
+        error_log("DPDatabase.inc - log_error $from_caller: $error");
         return _("An error occurred during a database query and has been logged.");
     }
 
@@ -196,13 +195,11 @@ final class DPDatabase
         }
 
         try {
-            $backtrace = debug_backtrace();
-            $caller = $backtrace[1]['file'] . ":" . $backtrace[1]['line'];
 
             $message = sprintf(
                 "%s %s %s\n",
                 date("c"),
-                $caller,
+                get_backtrace_loc(depth: 2),
                 preg_replace("/\s+/", " ", $sql)
             );
             $fp = fopen(DPDatabase::$tracing_log, 'a');

pinc/Project.inc

@@ -731,11 +731,8 @@ class Project
         }
 
         // If we don't recognize the property, raise a notice and return null
-        $trace = debug_backtrace();
         trigger_error(
-            'Undefined property via __get(): ' . $name .
-            ' in ' . $trace[0]['file'] .
-            ' on line ' . $trace[0]['line'],
+            "Undefined property via __get(): $name " . get_backtrace_loc(),
             E_USER_NOTICE
         );
         return null;

pinc/misc.inc

@@ -1664,6 +1664,26 @@ function validate_csrf_token(): void
     }
 }
 
+/**
+ *  @param int $depth
+ *     How deep in the call stack to get the location. 0 is the caller
+ *     of `get_backtrace_loc`, 1 is the caller of that function, etc
+ *  @return string
+ *     Returns a trace location like "in foo.php on line 742"
+ *     Omits the file name or linenumber clauses if they can't be found
+ */
+function get_backtrace_loc(int $depth = 1): string
+{
+    $trace = debug_backtrace();
+    $loc = [];
+    if (($file = $trace[$depth]["file"] ?? "")) {
+        $loc[] = "in $file";
+    }
+    if (($line = $trace[$depth]["line"] ?? "")) {
+        $loc[] = "on line $line";
+    }
+    return join(" ", $loc);
+}
 
 // XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX