Don't fail when commune code is missing or doesn't exist

src/lib/components/variables/VariableInput.svelte

@@ -277,7 +277,7 @@
     }
     const response = await fetch(
       new URL(
-        `/communes/${encodeURIComponent(code)}?field=distributions_postales`,
+        `/communes/${encodeURIComponent(code || "00000")}?field=distributions_postales`,
         $page.data.territoiresUrl,
       ).toString(),
       { headers: { Accept: "application/json" } },
@@ -290,7 +290,13 @@
       )
       return null
     }
-    const { distributions_postales } = await response.json()
+    const { distributions_postales, error } = await response.json()
+    if (error !== undefined) {
+      console.error(
+        `Error while retrieving commune from Insee code\n\n${JSON.stringify(error, null, 2)}`,
+      )
+      return null
+    }
     postalDistribution = `${distributions_postales[0].code_postal} ${distributions_postales[0].libelle_d_acheminement}`
     postalDistributionByInseeCode[code] = postalDistribution
     return postalDistribution