Revise various error messages (#1582)

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

src/core/jsonschema/bundle.cc

@@ -28,7 +28,7 @@ auto definitions_keyword(const std::map<std::string, bool> &vocabularies)
   // We don't attempt to bundle on dialects where we
   // don't know where to put the embedded schemas
   throw sourcemeta::core::SchemaError(
-      "Cannot determine how to bundle on this dialect");
+      "Could not determine how to perform bundling in this dialect");
 }
 
 auto embed_schema(sourcemeta::core::JSON &definitions,

src/core/jsonschema/frame.cc

@@ -521,7 +521,7 @@ auto SchemaFrame::analyse(const JSON &schema, const SchemaWalker &walker,
   const std::optional<std::string> root_base_dialect{
       sourcemeta::core::base_dialect(schema, resolver, default_dialect)};
   if (!root_base_dialect.has_value()) {
-    throw SchemaError("Cannot determine the base dialect of the schema");
+    throw SchemaError("Could not determine the base dialect of the schema");
   }
 
   std::optional<std::string> root_id{sourcemeta::core::identify(

src/core/jsonschema/jsonschema.cc

@@ -164,7 +164,8 @@ auto sourcemeta::core::reidentify(
   const auto base_dialect{
       sourcemeta::core::base_dialect(schema, resolver, default_dialect)};
   if (!base_dialect.has_value()) {
-    throw sourcemeta::core::SchemaError("Cannot determine base dialect");
+    throw sourcemeta::core::SchemaError(
+        "Could not determine the base dialect of the schema");
   }
 
   reidentify(schema, new_identifier, base_dialect.value());
@@ -339,7 +340,7 @@ auto sourcemeta::core::vocabularies(
       sourcemeta::core::base_dialect(schema, resolver, default_dialect)};
   if (!maybe_base_dialect.has_value()) {
     throw sourcemeta::core::SchemaError(
-        "Could not determine base dialect for schema");
+        "Could not determine base dialect of the schema");
   }
 
   const std::optional<std::string> maybe_dialect{
@@ -349,7 +350,7 @@ auto sourcemeta::core::vocabularies(
     // provide a explicit default, then we cannot do anything.
     // Better to abort instead of trying to guess.
     throw sourcemeta::core::SchemaError(
-        "Cannot determine the dialect of the schema");
+        "Could not determine the dialect of the schema");
   }
 
   return vocabularies(resolver, maybe_base_dialect.value(),