fix: address CodeRabbit review feedback

- Harden EagerEval.validate with type checks and strip() for empty strings
- Add _positional_alias for spreadsheet-style names beyond z (aa, ab...)
- Validate JSONata result is numeric before returning
- Add jsonata to requirements.txt

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

comfy_api/latest/_io.py

@@ -1431,7 +1431,11 @@ class EagerEval:
     def validate(self) -> None:
         if self.engine != "jsonata":
             raise ValueError(f"Unsupported EagerEval.engine '{self.engine}'. Only 'jsonata' is supported.")
-        if not self.expr and not self.expr_widget:
+        if self.expr is not None and (not isinstance(self.expr, str) or not self.expr.strip()):
+            raise ValueError("EagerEval.expr must be a non-empty string when provided.")
+        if self.expr_widget is not None and (not isinstance(self.expr_widget, str) or not self.expr_widget.strip()):
+            raise ValueError("EagerEval.expr_widget must be a non-empty string when provided.")
+        if self.expr is None and self.expr_widget is None:
             raise ValueError("EagerEval requires either 'expr' or 'expr_widget'.")
 
     def as_dict(self) -> dict[str, Any]:

comfy_extras/nodes_math.py

@@ -13,6 +13,19 @@ from typing_extensions import override
 from comfy_api.latest import ComfyExtension, io
 
 
+def _positional_alias(index: int) -> str:
+    """Convert 0-based index to spreadsheet-style column name: a..z, aa..az, ba..."""
+    s = ""
+    n = index
+    while True:
+        n, rem = divmod(n, 26)
+        s = chr(ord("a") + rem) + s
+        if n == 0:
+            break
+        n -= 1
+    return s
+
+
 class MathExpressionNode(io.ComfyNode):
     """Evaluates a JSONata expression against dynamically-grown inputs."""
 
@@ -53,11 +66,15 @@ class MathExpressionNode(io.ComfyNode):
     ) -> io.NodeOutput:
         context: dict = {}
         for i, (key, val) in enumerate(values.items()):
-            context[chr(ord("a") + i)] = val  # positional: a, b, c, ...
+            context[_positional_alias(i)] = val  # positional: a, b, c, ... aa, ab, ...
             context[key] = val  # also by input name: value0, value1, ...
         context["values"] = list(values.values())  # for $sum(values) etc.
 
         result = jsonata_lib.Jsonata(expression).evaluate(context)
+        if isinstance(result, bool) or not isinstance(result, (int, float)):
+            raise ValueError(
+                f"Math Expression must evaluate to a numeric result, got {type(result).__name__}."
+            )
         return io.NodeOutput(
             result, ui={"result": [result], "context": [context]}
         )

requirements.txt

@@ -24,6 +24,7 @@ av>=14.2.0
 comfy-kitchen>=0.2.7
 comfy-aimdo>=0.2.2
 requests
+jsonata
 
 #non essential dependencies:
 kornia>=0.7.1