Add additional error checking and warnings to stats route

src/mp_api/routes/search/models.py

@@ -54,6 +54,11 @@ class SearchStats(BaseModel):
         "estimator of the distribution, equally spaced "
         "between specified minimum and maximum values.",
     )
+    warnings: List[str] = Field(
+        None,
+        title="Warnings",
+        description="Any warnings generated while generating statistics.",
+    )
 
 
 class XASSearchData(BaseModel):

src/mp_api/routes/search/query_operators.py

@@ -212,13 +212,20 @@ def post_process(self, docs):
             min_val = self.min_val
             max_val = self.max_val
             num_samples = len(docs)
+            warnings = []
 
-            values = [d[field] for d in docs]
+            values = [d[field] for d in docs if field in d]
             if not min_val:
                 min_val = min(values)
             if not max_val:
                 max_val = max(values)
 
+            if len(values) != len(docs):
+                warnings += [
+                    "Some documents have field missing.",
+                    f"Only {len(values)} of {len(docs)} ({100*len(values)/len(docs):.2f}%) have {field} field present.",
+                ]
+
             kernel = gaussian_kde(values)
 
             distribution = list(
@@ -238,6 +245,7 @@ def post_process(self, docs):
                 distribution=distribution,
                 median=median,
                 mean=mean,
+                warnings=warnings,
             )
 
         return [response]