Add RBS type signatures for error classes

sig/react_on_rails/error.rbs

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+module ReactOnRails
+  class Error < StandardError
+  end
+end

sig/react_on_rails/json_parse_error.rbs

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+module ReactOnRails
+  class JsonParseError < ::ReactOnRails::Error
+    attr_reader json: String
+
+    def initialize: (parse_error: StandardError, json: String) -> void
+    def to_honeybadger_context: () -> Hash[Symbol, untyped]
+    def raven_context: () -> Hash[Symbol, untyped]
+    def to_error_context: () -> Hash[Symbol, untyped]
+  end
+end

sig/react_on_rails/prerender_error.rbs

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+module ReactOnRails
+  class PrerenderError < ::ReactOnRails::Error
+    MAX_ERROR_SNIPPET_TO_LOG: Integer
+
+    attr_reader component_name: String?
+    attr_reader err: StandardError?
+    attr_reader props: String?
+    attr_reader js_code: String?
+    attr_reader console_messages: String?
+
+    def initialize: (?component_name: String?, ?err: StandardError?, ?props: String?, ?js_code: String?, ?console_messages: String?) -> void
+    def to_honeybadger_context: () -> Hash[Symbol, untyped]
+    def raven_context: () -> Hash[Symbol, untyped]
+    def to_error_context: () -> Hash[Symbol, untyped]
+
+    private
+
+    def calc_message: (String? component_name, String? console_messages, StandardError? err, String? js_code, String? props) -> [String?, String]
+    def build_troubleshooting_suggestions: (String? component_name, StandardError? err, String? console_messages) -> String
+  end
+end

sig/react_on_rails/smart_error.rbs

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+module ReactOnRails
+  class SmartError < Error
+    attr_reader error_type: Symbol
+    attr_reader component_name: String?
+    attr_reader props: String?
+    attr_reader js_code: String?
+    attr_reader additional_context: Hash[Symbol, untyped]
+
+    def initialize: (error_type: Symbol, ?component_name: String?, ?props: String?, ?js_code: String?, **untyped additional_context) -> void
+    def solution: () -> String
+
+    private
+
+    def build_error_message: () -> String
+    def error_type_title: () -> String
+    def error_description: () -> String
+    def component_not_registered_solution: () -> String
+    def missing_auto_loaded_bundle_solution: () -> String
+    def hydration_mismatch_solution: () -> String
+    def server_rendering_error_solution: () -> String
+    def redux_store_not_found_solution: () -> String
+    def configuration_error_solution: () -> String
+    def default_solution: () -> String
+    def additional_info: () -> String
+    def troubleshooting_section: () -> String
+    def find_similar_components: (String name) -> Array[String]
+  end
+end